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Author Topic: Help needed with a linear actuator motor controller  (Read 1656 times)

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Offline PJV SL-CTopic starter

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Help needed with a linear actuator motor controller
« on: July 28, 2014, 06:38:32 AM »

  First time post - hoping I can find some help with a project I am working on.  Not exactly "robot" related, this is a custom car project and I am controlling the doors/front clip/rear clip with 12v linear actuators.

  I have an ISIS system controlling the car electronics, including 2 of their optional components that allow me to control items via an ISIS supplied RF transmitter as well as an android smartphone. 

  The actuators are controlled by an Autoloc motor controller.  You can program the run time for an actuator and when the motor controller sees a ground signal, it runs the actuator for the programmed time and then stops.  Next time the motor controller sees ground, it reverses the polarity and runs the actuator in the reverse direction for the same time.  If at any time during the up/down travel, it sees a ground signal, it stops the actuator.  When it sees ground again, it reverses the polarity and the actuator runs the same distance in the opposite direction.

The problem.

The motor controllers allow for a certain amount of adjustability for "sensitivity".  Even on the controllers highest setting, it is sometimes not enough to operate the doors.  There is no binding, the actuators have well over the weight rating needed and in fact work 100% of the time if I run power directly to the actuator motor.  When the doors are acting up/stalling on the open cycle, very slight one finger pressure assisting allows it to run the full travel without stopping.

I have searched for other motor controllers that might allow more adjustability of the force, but have not found anything with the features I need.  So I am left with trying to improve the ones I have.

Does anyone have any experience with these motor controllers or have any idea how I might modify them to do what I need?

Here is a link to see the actuators working:

Also, I attached a picture of the different parts/how they work together.


Offline bdeuell

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Re: Help needed with a linear actuator motor controller
« Reply #1 on: July 29, 2014, 10:28:50 PM »
It sounds to me like the motor controller is either not running at 100% duty cycle (if it even uses PWM for variable speed, it wasnt clear to me if this is a capability)
Or there is a voltage drop across the controller (possibly due to the shunt resistor used in current measurement)

To test for either of these condtions you could measure the voltage at the input of the controler and the output while the actuator is moving, it would be a good idea to also measure the voltage of your power source without load as a refrence. If you cant figure it out post what your voltage readings are for these three locations and we will see if we can help.

Assuming one of the above condtions is the issue I have a few soutions:

Find a new contorller that can deilver full power to the motors
Get new actuators that will work with your existing system
increase the suply voltage (assuming you can do so safely without damaging your components)
use a spring to assist your actuators and reduce the load

One other possible source for the difference in opperation, when you tested the actuators connected directly to your power source did you run both at once?

Also, it moght help if you can post the documentation/datasheets for your components.

I hope you have thought about what happens when you leave the headlights on and the battery dies.
Also what happens if the door gets out of position, for example when it is openend it gets pushed open a little further...will it close all the way?

Offline PJV SL-CTopic starter

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Re: Help needed with a linear actuator motor controller
« Reply #2 on: July 30, 2014, 01:32:53 PM »
Really appreciate you reading and responding to my post!  The actuators are very basic, no positioning logic, no variable speeds.  I will try to take some voltage readings tonight.

The documentation just doesn't exist unfortunately and there is no tech support    :-\

I have run both actuators at the same time in my early testing and it wasn't a problem.

I should also note, I did this same install in 2 other cars and....over time, the same problems have surfaced with those cars. 

The ISIS system has an optional module (which I have installed) to monitor battery voltage.  When it drops below a certain level, (due to leaving the headlights or because of parasitic draw when the car sits for weeks), it shuts off the power.  So in theory, when you come back to the car, you hit the reset button and there is still enough juice to start the car.  I have reset buttons inside and outside the car.  I also have a (secret) option for opening the door from the outside or inside in the event I have some catastrophic problem with anything related to the door systems.

The doors cannot really be pushed out of position.  You can stop them anywhere along their travel and then restart and it isn't a problem.

I have looked far and wide for a better controller and not found anything yet that matches what I need it to do.


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